Electromagnetic compensating device.



ELECTROMAGNETIC OOMPENS'ATING DEVICE. APPLICATION FILED HAY24,1904.

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MZ OCWJA R PATENTED AUG. 22, 1905.

B. A. STOWB ELECTROMAGNETIC GOMPBNSATING DEVICE.

APPLICATION FILED MAY 24, 1904.

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No. 797,628. PATENTED AUG. 22, 1905. B. A. STOWE. ELECTROMAGNETICGOMPENSATING DEVICE.

APPLICATION YILED MAY 24, 1904.

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UNITED STATES PATENT OFFICE.

BERNARD A. STOWVE, OF CLEVELAND, OHIO, ASSIGNOR TO THE JANDUS ELECTRICCOMPANY, OF CLEVELAND, OHIO, A CORPORATION OF OHIO.

Specification of Letters Patent.

Patented Aug. 22, 1905,

Application filed May 24, 1904. Serial No. 209,459.

To all whom, it may concern:

Be it known that I, BERNARD A. STowE, a citizen of the United States,and a resident of Cleveland, county of Cuyahoga, and State of Ohio, haveinvented a new and useful Improvement in Electromagnetic CompensatingDevices, of which the following is a specification, the principle of theinvention being herein explained and the best mode in which I havecontemplated applying that principle, so as to distinguish it from otherinventions.

My invention relates to electromagnetic compensating devices, as appliedto the compensation for variations of conditions, and particularly tothe compensation for the variations of electrical conditions inarc-lamps due to the variation of temperature resulting from the heatgenerated by the resistance of the electrical circuit in such lamps.

Said invention consists of means hereinafter fully described, andparticularly set forth in the claims.

The annexed drawings and the following description set forth in detailcertain mechanism embodying the invention, such disclosed meansconstituting but oneof various mechanical forms in which the principleof the invention may be used.

.In said annexed drawings, Figure 1 represents the main portion of aninclosed arc constant-current lamp embodying my invention. Fig. 2represents a section of the operating magnet-coil of the lamp, takenupon a horizontal plane and looking upward, the winding of such magnetbeing indicated in dotted lines. Fig. 3 represents a vertical axialsection of said magnet, showing part of the magnet-cores in elevation.Figs. 4 and 5 represent perspective views of details of said magnet.Fig. 6 represents an axial section of a portion of said magnet,illustrating a change of relative position of parts thereof. Figs. 7 and8 represent detail views of a modified form of device embodying myinvention.

The general construction of the lamp, the main portion of which isillustrated, is that of constant-current lamps now in general use, inwhich a main electromagnet A, whose armature A is actuated by thelamp-current to establish the are by moving the upper carbon C, and ashunt electromagnet B, whose action is opposed to that of magnet A andis provided for regulating and modifying such actuation. This mechanismis mounted upon a suitable frame. It has been found that the characterof the movement of the armature is influenced by the temperature of themagnetsthat is, when the latter are heated a more marked action isobtained than when the magnets are cold. Unless, therefore, means forcompensating for the action of the heat acquired by the operation of thelamp be provided a constancy of action of the magnet, and hence aconstancy of conditions at the arc, is not obtained under the sameconditions in the circuit. Let it be assumed that the lamp is of theusual construction, is cold, and that the mechanism is set so that agiven current will effect an actuation of the armature so as to .producea required voltage at the arc. The current now being turned on a givenarc will be obtained. As the lamp continues to operate the mechanism,including the magnets A and B, becomes heated. Such heating decreasesthe electrical conductivity of the thin copper wire of the shuntcoil Bby reason of its temperature coefficient of resistance, but does notmaterially affect the conductivity of the wire of coil A as a result ofits larger cross-sectional area and fewer turns. The magneticconductivity of the two magnets is, on the other hand, increased; butsince the action of the two magnets is opposed in this form of lamp anyvariation in the action of one magnet by reason of temperature variationis compensated for by a substantially similar variation in the othermagnet. In following the effect of changes in temperature in thestructure illustrated the normal changes in magnetic conductivity mayhence be disregarded. The electrical conductivity of the wire of theshunt-magnet B being decreased and its resistance correspondinglyincreased, a lesser part of the current flows through coil B than beforeand a greater quantity through coil of magnet A, thus increasing theactuating effect of the armature actuated by said magnet A, drawing thecarbons farther apart and increasing the voltage at the arc. Thecharacter of the are changes correspondingly, so that it will be seenthat an arc of one character is produced at the beginning of the lampsoperation and an arc of a diiferent character is produced after themechanism becomes heated. In order to correct this deficiency, I providea structure in which such changes are compensated for and an areproduced which will have substantially the same illuminating qualitiesat substantially all periods of its operation and throughout all of thechanges of temperature to which the lamp mechanism is subjected. Suchstructure is embodied in the operating-magnet A and is illustrated inFigs. 2, 3, 4, 5, and 6. Said magnet consists of a yoke 6, two cores 6b, the usual spools b b and their windings, together with other partswhich will be described. Each core 7) is connected with the yoke b bymeans of a screw passing therethrough, an elastic washer I) beinginterposed between said yoke and the screws head, so that it will beseen such core is yieldingly secured to the yoke and may be caused torecede slightly therefrom. Enveloping each such core is a metallic shellIf, which under normal conditions-that is, when the parts are of normalor atmospheric temperatureis of a length such that one end of the shellabuts the inside surface of the yoke and the opposite end abuts ashoulder b on the core. Said shell is constructed of a metal, such aszinc, which has a coefficient of expansion greater than that of the ironcore I), so that an increase in temperature will cause it to expand inthe direction of the cores axis, and so cause the core to recede fromthe yoke, as shown in exaggerated form in Fig. 6. It will therefore beseen that the conductor of magnetic lines of force, consisting of theyoke and core, has its magnetic conductivity afl'ected by such breakingof the normal connection established between the several parts of saidconductor. An increase in temperature of magnet A due to the heatgenerated during its operation and the consequent concomitant increasein the degree of action of the said magnet A, previously described, istherefore compensated for by a decrease in the conductivity at the jointbetween the core and yoke of the magnet A. The latters parts are soarranged that such increase of conductivity is caused to besubstantially directly proportionate to the increase of magnetic actionupon the armature of magnet A, which would be normally affected by theincreased flow of current through the coil thereof resulting from thedecreased electrical conductivity of magnet B, so that the character ofthe modified action of the magnet effected by the compensating means,and hence the conditions at the are, remains substantially constantthroughout such variations of temperature as are experienced by the lampmechanism during the period included between the beginning of the lampsoperation, when the temperature of its mechanism is normal, and suchtime as such mechanism attains its maximum temperature.

In Figs. 7 and 8 I have illustrated a second form of core constructionwhich embodies the principles of the above-described invention and whichI have found embodies advantages not present in the first-describedstructure. In this structure the yoke b is of the previously-describedconstruction; but the core is divided into two unequal parts 6 and If.The lower or short part If is secured to the yoke and caused to normallyabut the lower end of part b by means of a long screw 6, passing througha bore 6", as shown. The shell 5'' as before abuts the under surface ofthe yoke and a shoulder Z), formed upon the part 7/ intermediate of itsextremities. The diameter of part b is such that it will fit tightly inshell 5 The expansion of shell 7) hence causes the two parts of the coreto separate, as shown in Fig. 8, part 5 remaining fixed relatively toyoke I), the elastic washer 7)" being provided, as before. The magneticleakage will hence take place at the plane of separation of the twoparts Z2 and 7), as will be readily understood. The location of thisplane of leakage at the lower portion of the magnetic circuit instead ofat the top, as in the first-described structure, I have found rendersthe operation of the device more delicate and reliable. in this modifiedform the part b may be considered part of the yoke in so far as relatesto the similarity of construction and operation of the two forms of theabove-described invention. The lower part 7) of the core would in suchevent correspond with the core 7) of the first-described device. Thesaid modified form, then, may be structurally considered as merelyembodying the shortening up of core 5' and the extensions of the yokeinto the coil to complete the magnetic circuit and form part of thecore.

Other modes of applying the principle of my invention may be employedinstead of the one explained, change being made as regards the mechanismherein disclosed provided the means stated by any one of the followingclaims or the equivalent of such stated means be employed.

I therefore particularly point out and distinctly claim as myinvention 1. 1n an electromagnetic compensating device, the combinationwith a magnetic conductor, of means for positively varying the magneticconductivity thereof concomitantly with a change in temperature of themagnetcoil and inversely relatively to such temperature.

2. The combination with actuating means including an electromagnet andnormally affected by temperature variations, the action of such meansbeing positively affected by an increase in temperature of partsthereof, of means for controlling the magnetic conductivity of saidelectromagnet to compensate for such positive increment so as tosubstantially maintain a constancy of action of said actuating means.

3. In an electromagnetic compensating device, the combination with amagnetic conductor comprising two elements yieldingly held in contactwith one another, of a member operatively connected with said twoelements and having a coeflicient of expansion greater than that of oneof said elements, whereby temperature variations will effect the degreeofcontact of said elements.

4. In an electromagnetic compensating device, the combination with amagnetic conductor including two elements yieldingly held injuxtaposition, of a member operatively connected with said two elementsand having a coeflicient of expansion greater than that of saidconductor.

5. In an electromagnetic compensating device, the combination with amagnetic conductorincluding two elements yieldingly held injuxtaposition, of a member mounted upon and operatively engaging one ofsaid elements, engaging the other of said elements, and having acoeflicient of expansion greater than that of said conductor.

6. In an electromagnetic compensating de vice, the combination with amagnetic conductorincluding two elements yieldingly held injuxtaposition, 0 an expansible member mounted between said two elementsand having a coefiicient of expansion greater than that of saidconductor.

7. In an electromagnetic compensating device, the combination with amagnetic conductor comprisingayoke and a core yieldingly connectedtherewith, of an expansible member mounted between said yoke and core,and having a coeificient of expansion greater than that of the conductorparts adjacent to it.

8. In an electromagnetic compensating device, the combination with amagnetic conductor comprising two separable parts normally held incontact, of means controlled by temperature for determining the positionof said parts relatively to each other.

9. In an electromagnetic compensating device, the combination with amagnetic conductor, of means controlled by temperature for efiectingmagnetic leakage in said conductor.

10. In an electromagnetic compensating device, the combination of amagnetic conductor comprising two separable parts, yielding meansconnecting said two parts, and a metallic member rigidly mountedrelatively to the one part engaging the other part, and hav ing acoeflicient of expansion greater than that of said conductor.

11. In an electromagnetic compensating device, the combination of amagnetic conductor comprising two juxtapositioned separable parts;yielding means connecting said two parts, and a hollow cylinder of Zincor similar material having a coefficient of expansion greater than ironsurrounding said conductor engaging the one conductor part and rigidlymounted relatively to the other part.

12. In an electromagnetic compensating device, the combination of a mainelectromagnet, a second electromagnet having its coil connected in shuntwith the main-magnet coil, and means for varying the magneticconductivity of the main magnet concomitantly with a change intemperature of the coil of the shunt-magnet.

13. In an electromagnetic compensating device, the combination of amain-magnet coil, a shunt-magnet coil, a separable magnetic conductor inthe field of said main coil, and automatically-operating means foreffecting the separation of said conductor concomitantly with anincrease in temperature of the shuntmagnet coil.

14. In an electromagnetic compensating device, the combination of amagnet-coil, a separable core in the field of said coil, andautomatically-operating means for effecting the separation of said coreconcomitantly with an increase in the flow of current through said coil.

Signed by me this 12th day of May, 1904.

BERNARD A. STOWVE.

Attest:

A. E. M'ERKEL, HENRY J. VOGT.

